The Bush Breaker is a titanium chainbreaker, spoke wrench, valve core remover, and disc rotor truing tool - In the most compact form I could create.
Machined from Grade 5 titanium, the Bush breaker includes tools one would want to have on an extended or remote bike ride, but not necessarily a short ride: As a standalone tool, riders don’t have to carry what they don’t need on short outings close to home. The tool can be used in a home toolkit, ready to take with when greater adventures call.
Inspired by Charlie’s intention for an ultralight chain tool, I thought the design worth revisiting. So I got to work modeling what is primarily a chain tool, with other features built in that users would want on rides where carrying a chain tool felt necessary. The other features are:
spoke wrench
valve core remover
rotor truing tool
Where optimizing for certain functions would compromise the effectiveness of the chain tool, these secondary functions were eliminated in favor of ones better suited to the form of a chain tool. For the rotor truing function, the tool engages the 10mm flats of the Link Wrench for leverage (see gallery at bottom). Given the common M6 x 1mm thread of the chain pin, the Bush Breaker can be used as an upgrade to common multi-tools with built-in chain pin removers (final photo in gallery).
In the 1990’s, a design hero of mine, Charlie Cunningham made a chain tool called the “Chain Pup” - by far the lightest portable chain breaker at the time. However it lacked additional functions that I saw ways to add.
Making this prototype stretched my machining capabilities given the part geometry and challenge of working with titanium. I planned each operation carefully, waiting to tap threads in certain holes that would be used as locating features - and utilized my diamond grinder to reduce the diameter of a carbide endmill (shown on left) such that it would fit within previously milled features. By making light cuts to account for the decrease in tool rigidity, the operation was successful.
